The map collection at the Leibniz Institute for East and Southeast European Studies comprises about 8,300 maps from the 16th to the 21st century. In addition, there is a catalogue of hidden maps with over 27,000 entries, electronically accessible within the framework of the DFG project GeoPortOst . The catalogue lists maps printed in monographs, series and journals.

The digital map collection of the IOS, which can be accessed via the geoportal , is constantly being expanded and comprises a large part of the old maps as well as a selection of hidden maps (as of January 2020: 3,027 maps).